This invention relates to water driven fans and in particular to high velocity, high pressure rise fans.
Removal of smoke or other hazardous gases from remote spaces such as encountered during or following a fire in high rise buildings, ships and mine shafts may require that such gases or the fresh air, be transported through long ducts at high gas flow or air flow velocities. Also it is desirable that such high powered fans be light enough to be transportable by a single person in time of emergency. Very often such fans must be capable of operating in either toxic or volatile enviroments and must be explosion proof. Also, in many instances, at the fire locations such as in high rise buildings, the electric power may be lost while the main fire lines are able to deliver water at pressure required for fire fighting. In many cases operation of gasoline driven fans in confined spaces are restricted or prohibited.
The use of water turbines to drive fans is well known to the art. For example, U.S. Pat. No. 3,607,779 by Earle C. King illustrates the use of a radial inflow water turbine at the front end of the shaft driving a relatively low pressure rise axial fan and a foam concentrate pump at the rear end of the shaft. U.S. Pat. No. 4,597,524 by Stig L. Albertsson describes a snow making machine with air flow fan being belt driven by a multistage water turbine. U.S. Pat. No. 3,141,909 by H. A. Mayo, Jr. describes turbine drive for cooling tower fan utilizing an radial outflow water turbine driving a fan.
Radial inflow or outflow turbines require relatively large space envelopes. Such an arrangement is feassible when driving relatively large diameter fans, but when a small diameter, high speed, high pressure rise fan is needed, the radial flow turbine can interfere with the air flow through the fan. Belt driven fans are generally combersome and relatively heavy.
It is an objective of the present invention to provide a water turbine driven fan for which the turbine drive is submerged inside the main airflow stream and furthermore that such turbine drive will not obstruct to any significant degree the usually high velocity airflow associated with such high pressure rise axial fans.
It is a further objective that the turbine envelope be substantially reduced in size below the present state of the art of the fan turbine drives. Such turbine drive should preferably fit well within the envelope of the relatively small hub diameter associated with such high velocity fan impellers. Also, in order to allow for an aerodynamically efficient design of the axial fan diffuser, the rear section of the hub diameter must be further reduced constraining even more the avaliable envelope for the drive turbine. It would be therefore desirable to incorporate a water turbine which is appropriatly matched with the fan driving requirements and which will occupy a small envelope while generating relatively large driving power at high hydraulic efficiencies.